초록 ▼

An aftertreatment device for reducing nitrogen oxides (NOx), particulate matter (PM), hydrocarbon (HC), and carbon monoxide (CO) generated by a compression-ignition (CI) engine. In this device, lean exhaust air generated in the CI engine is converted to rich exhaust air, and energy used for the conv

An aftertreatment device for reducing nitrogen oxides (NOx), particulate matter (PM), hydrocarbon (HC), and carbon monoxide (CO) generated by a compression-ignition (CI) engine. In this device, lean exhaust air generated in the CI engine is converted to rich exhaust air, and energy used for the conversion is recycled using an energy recovery device. The result rich exhaust air then pass through an oxidation catalyst, where NOx is reduced with CO and HC.

대표청구항 ▼

1. An emission control apparatus for an engine comprising: a catalyst in which NOx in exhaust air is effectively reduced through direct reactions with hydrocarbon and carbon monoxide in an air-to-fuel ratio window with its lower bound lower than a stoichiometric air-to-fuel ratio and its upper bound

1. An emission control apparatus for an engine comprising: a catalyst in which NOx in exhaust air is effectively reduced through direct reactions with hydrocarbon and carbon monoxide in an air-to-fuel ratio window with its lower bound lower than a stoichiometric air-to-fuel ratio and its upper bound higher than said stoichiometric air-to-fuel ratio;at least one combustion device positioned upstream from said catalyst with a fuel supply configured to enrich lean exhaust air produced from said engine;at least one energy conversion device for converting heat energy into other forms of energy;a Diesel Particulate Filter (DPF) downstream from the combustion device and upstream of the catalyst for removing particulate matter produced from said engine;a heat exchanging device including a first inlet configured to receive an exhaust air flow, a second inlet fluidly coupled to an outlet of said DPF, a fist outlet fluidly coupled to an inlet of said combustion device, and a second outlet configured to release said exhaust air flow;a first bypass valve with its inlet fluidly connected to said first inlet of said heat exchanging device, and its outlet fluidly connected to said first outlet of said heat exchanging device;a second bypass valve with its inlet fluidly connected to said second inlet of said heat exchanging device, and its outlet fluidly connected to said second outlet of said heat exchanging device;a bypass controller configured to close said first bypass valve and said second bypass valve in said process for regenerating said DPF;a feedback oxygen sensor positioned downstream from said combustion device providing downstream sensing signals indicative to an air-to-fuel ratio of an exhaust air flow produced by said engine; anda system controller configured to reduce NOx from said exhaust air flow passing through said catalyst by controlling a fuel delivering rate of said fuel supply to said combustion device to maintain said air-to-fuel ratio of said exhaust air flow within said air-to-fuel ratio window, in response to at least said downstream sensing values obtained from said feedback oxygen sensor, and a mass flow rate of exhaust air produced from said engine, when a NOx level in said exhaust air flow produced by said engine is higher than a predetermined value determined by an emission regulation. 2. The emission control apparatus of claim 1, wherein said system controller is further configured to use an air-to-fuel ratio of said engine to control said fuel delivering rate of said fuel supply. 3. The emission control apparatus of claim 2, further comprising: a feed-forward oxygen sensor positioned in-between said engine and said combustion device providing upstream sensing values indicative of said air-to-fuel ratio of said engine. 4. The emission control apparatus of claim 2, wherein said system controller is further configured to control said fuel delivering rate of said fuel supply by integrating a feed-forward control signal, which is produced by a feed-forward control loop in response to at least said upstream sensing values provided by said feed-forward oxygen sensor, together with a feedback correction control signal, which is generated by a feedback control loop according to a difference between a target value determined by said air-to-fuel ratio window and said downstream sensing values obtained from said feedback oxygen sensor. 5. An emission control apparatus for an engine comprising: a Diesel Particulate Filter (DPF) for removing particulate matter produced from said engine;a first heating device including a Diesel Oxidation Catalyst (DOC) positioned upstream from said DPF;a dosing device with an injector positioned upstream from said DOC and downstream from said engine for delivering a hydrocarbon fuel in dosing pulses into an exhaust air flow;a second heating device including a heating element positioned downstream from said injector of said dosing device for heating said hydrocarbon fuel delivered by said dosing device above its light-off temperature before it is mixed with said exhaust air flow;a heat exchanging device including a first inlet configured to receive an exhaust air flow, a second inlet fluidly coupled to an outlet of said DPF, a first outlet fluidly coupled to an inlet of said DOC, and a second outlet configured to release said exhaust air flow;a first bypass valve with its inlet fluidly connected to said first inlet of said heat exchanging device, and its outlet fluidly connected to said first outlet of said heat exchanging device;a second bypass valve with its inlet fluidly connected to said second inlet of said heat exchanging device, and its outlet fluidly connected to said second outlet of said heat exchanging device;a bypass controller configured to close said first bypass valve and said second bypass valve in said process for regenerating said DPF;a temperature sensing means for generating temperature sensing signals indicative to a temperature of said DOC; anda preheating controller configured to generate a driving signal in a process for regenerating said DPF, energizing said heating element of said second heating device in response to said dosing pulses delivered by said dosing device when said temperature sensing values obtained from said temperature sensing means are lower than a first predetermined threshold, and de-energizing said heating element of said second heating device when said temperature sensing values are higher than a second predetermined threshold. 6. The emission control apparatus of claim 5, wherein said driving signal is a pulse signal. 7. The emission control apparatus of claim 5, wherein said heating element is an electrical heater and said pre-heating controller is further configured to generate a pulse control signal energizing and de-energizing said electrical heater by discharging and charging a capacitor array, which includes at least one capacitor. 8. The emission control apparatus of claim 5, wherein said heating element of said second heating device is a fuel burner with a fresh air supply, a fuel supply, and an ignition control means for controlling igniting operations. 9. The emission control apparatus of claim 1, further comprising: an air compressing means positioned in said exhaust flow upstream from said heat exchanging device; anda pressure controller configured to operate at least said air compressing means in controlling a back pressure of said engine below a predetermined limit value. 10. An emission control apparatus for an engine comprising: a Diesel Particulate Filter (DPF) for removing particulate matter from exhaust air;a Diesel Oxidation Catalyst (DOC) positioned upstream from said DPF for oxidizing hydrocarbon and carbon monoxides;an exhaust air compressing means for producing a higher pressure exhaust flow from a low pressure inlet configured to receive a low pressure exhaust air flow and a high pressure outlet for releasing a compressed exhaust air flow;a heat exchanging device including a first inlet configured to receive said compressed exhaust air flow released from said air compressing means, a second inlet fluidly coupled to an outlet of said DPF, a first outlet fluidly coupled to an inlet of said DOC, and a second outlet configured to release said compressed exhaust air flow;a first bypass valve with its inlet fluidly connected to said first inlet of said heat exchanging device, and its outlet fluidly connected to said first outlet of said heat exchanging device;a second bypass valve with its inlet fluidly connected to said second inlet of said heat exchanging device, and its outlet fluidly connected to said second outlet of said heat exchanging device;a bypass controller configured to close said first bypass valve and said second bypass valve in said process for regenerating said DPF; anda pressure controller configured to operate at least said exhaust air compressing means in controlling a back pressure of said engine below a predetermined limit value. 11. The emission control apparatus of claim 10, further comprising: a NOx removal catalyst positioned downstream from said heat exchanging device having NOx effectively reduced inside through direct reactions with hydrocarbon and carbon monoxide in an air-to-fuel ratio window with its lower bound lower than a stoichiometric air-to-fuel ratio and its upper bound higher than said stoichiometric air-to-fuel ratio;at least one combustion device positioned upstream from said NOx removal catalyst with a fuel supply configured to enrich lean exhaust air produced from said engine;at least one energy conversion device positioned downstream from said combustion device for converting heat energy into other forms of energy;a feedback oxygen sensor positioned downstream from said combustion device providing sensing signals indicative to an air-to-fuel ratio of an exhaust air flow passing through said NOx removal catalyst; anda system controller configured to control an fuel delivering rate of said fuel supply to said combustion device to maintain said air-to-fuel ratio of said exhaust air flow passing through said NOx removal catalyst in a target range determined by said air-to-fuel ratio window during deNOx operations, according to at least said sensing values obtained from said feedback oxygen sensor, and a mass flow rate of exhaust air produced from said engine. 12. The emission control apparatus of claim 10, further comprising: a NOx removal catalyst positioned downstream from said heat exchanging device having NOx in exhaust air effectively reduced through direct reactions with hydrocarbon and carbon monoxide in an air-to-fuel ratio window with its lower bound lower than a stoichiometric air-to-fuel ratio and its upper bound higher than said stoichiometric air-to-fuel ratio;at least one oxygen sorption device including oxygen sorption materials absorbing and desorbing oxygen positioned upstream from said NOx removal catalyst; anda controller configured to operate said oxygen sorption device to maintain an air-to-fuel ratio of an exhaust air flow passing through said NOx removal catalyst in a target range determined by said air-to-fuel ratio window during deNOx operations. 13. The emission control apparatus of claim 12, wherein said oxygen sorption device includes at least two functional sections working sequentially in removing oxygen from said exhaust air flow passing through said NOx removal catalyst. 14. The emission control apparatus of claim 13, wherein said functional sections include a working section, in which a rich exhaust flow is produced with oxygen being adsorbed from a lean exhaust air flow before entering said NOx removal catalyst, and a regeneration section, in which oxygen is desorbed to said rich exhaust air flow after passing through said NOx removal catalyst. 15. The emission control apparatus of claim 14, wherein said oxygen sorption materials include perovskite-related oxides.